1. Field of the Invention
This invention relates to a flow control valve.
2. Description Prior Art
Such valves are generally known. They are installed in a pipeline and their purpose is to control the flow through this pipe or, to state it more precisely, to monitor it. This monitoring function can be a result of the valve not letting more fluid flow through than has been pre-determined, even if pressure on the supply side increases. Therefore its function is more extensive than that of a simple throttle valve. A flow control valve can also block flow-through, if too much fluid flows through. A flow control valve can also block small amounts of flow-through, such as occurs in case of leaks.
With excessive flow-through, such as occurs in the case of a bursting pipe or when a hose bursts, the flow control valve should close as rapidly as possible, while the interruption of the flow-through does not necessarily have to be performed rapidly.
In certain cases, for example with washing machines, is admitted during defined cycles over a defined length of time. This water admittance time is controlled by electromagnetic valves.
If such a valve becomes stuck, the result can be flooding In this instance it is advantageous to install a flow control valve in the supply pipe, which blocks the flow after the defined flow-through time has been exceeded. To manage all the above mentioned control functions, conventional flow control valves by themselves or in combination with other valves can perform these functions. If a plurality of valves are required for performing the desired control functions, the installation becomes rather expensive. This is the case when, in addition to the valve operated by the pressure of the flowing fluid, a valve which is operated by external energy, for example an electric valve, is required. Most flow control valves known today vary in construction, depending on whether they are intended to perform one or the other control function. In most cases the known flow control valves are designed in such a way that they can only perform one or at most two of the desired control functions. This makes the production of such flow control valves more expensive and also hampers their universal application, which would be advantageous in the interest of safety.
From Swiss Patent Application No. 00598/91-0 a flow control valve with a housing is known, in which a fixed insert is installed, around all sides of which liquid can flow, such valve comprises a guide cylinder with a spring-loaded control element on the inlet side and a main cylinder on the outlet side which adjoins the guide cylinder and has a guided spring-loaded closing piston. During zero flow-through the control element has a disk valve which closes off the inlet opening, with a shaft guided in the guide cylinder, wherein the shaft and the disk have central through-bores. A centrally located sealing element is maintained in the bottom of the guide cylinder, next to which at least one through-opening from the guide cylinder to the main cylinder remains free. Depending on the closing characteristic the flow control valve has, the sealing element disposed in the guide cylinder must be fixedly or elastically maintained. It has been shown that unwanted oscillations can occur with an elastically spring-mounted fastening. Thus it is almost impossible to define the reaction threshold clearly. Also in case of a burst pipe or any other sudden pressure drop on the outlet side the valve closes comparatively slowly because closing is performed by the closing piston.